252 GENETICS: C. C. LITTLE Proc. N. A. S. 
TABLE 2 
1st births 
SUBSEQUENT BIRTHS 
Q Q 
Ratio 
Q 9 
Ratio 
Difference 
i) 
o 
a 
a; 
Ur 
to 
Q 
u 
0 
u 
0 
u 
European Pure 
B. W. I. Colored 
European Hybrid 
U. vS. White 
U. S. Colored 
1236 
313 
303 
534 
264 
1070 
302 
250 
446 
282 
115.51 ± 1.5 
103.64 =t 2.75 
121.20 ^ 3.14 
119.73 ± 2.26 
93.61 =t 2.44 
1571 
354 
374 
460 
431 
1614 
316 
301 
394 
441 
97.33 ± 1.18 
112.02 ± 2.76 
124.25 ± 2.91 
116.75 ± 2.49 
97.73 ± 2.03 
18.18 ± 1.86 
8.38 =t 3.9 
3.05 ± 4.28 
2.98 ± 3.36 
4.12 =b 3.17 
9.7 
2.1 
0.7 
0.9 
1.3 
Table 2 shows that the three hybrid matings show a not significant 
difference between the sex ratio of offspring of primipara and those of subse- 
quent births. On the other hand, there is a marked significance in the 
case of European pure matings and a barely possibly significant differ- 
ence in the B. W. I. colored. The entire excess of male births in the total 
sex ratio of 104.54 in the European pure matings is found in the offspring 
of primipara — where 115.51 1.50 males to 100 females are found. 
It is interesting to note that the negro matings in every case differ from 
one another in exactly the opposite direction from the white races. Thus 
if the direction of arrows shows the change in the male ratio the follow- 
ing diagram may be constructed: Single arrows = white, double arrows = 
colored. 
Ratio of 
males per 
100 females 
120 
115 
110 
100 
95 
J^^Birfhs Sulpsecfuenf B/rfhs Fure Hcjbrid 
FIG. 1 
